1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, more particularly, to an LCD device including a driving integrated circuit (IC) that can be protected against heat thereof.
2. Description of the Related Art
Flat panel display (FPD) devices that have a relatively light weight, a thin profile, and a low power consumption characteristics are being developed and commonly used as a substitute for cathode ray tube (CRT) devices. Generally, display devices may be classified according to their ability for self-emission, and may include emissive display devices and non-emissive display devices. Emissive display devices display images by taking advantage of their ability to self-emit light, while the non-emissive display devices require a light source because they do not emit light by themselves. For example, plasma display panel (PDP) devices, field emission display (FED) devices, and electroluminescent display (ELD) devices are commonly used as emissive display devices. Liquid crystal display (LCD) devices, which may be categorized as non-emissive display devices, are commonly used in notebook and desktop computers because of their high resolution, capability of displaying color images, and high quality image display.
A LCD module of an LCD device includes an LCD panel for displaying images to an exterior of the LCD panel and a backlight unit for supplying light to the LCD panel. The LCD panel normally includes two substrates facing and spaced apart from each other, and a liquid crystal material interposed therebetween. Liquid crystal molecules of the liquid crystal material have a dielectric constant and refractive index anisotropic characteristics due to their long, thin shape. In addition, two electric field generating electrodes are formed on the two substrates, respectively. Accordingly, an orientation alignment of the liquid crystal molecules can be controlled by supplying a voltage to the two electrodes, wherein transmittance of the LCD panel is changed based on the polarization properties of the liquid crystal material. However, since the LCD panel is a non-emissive-type display device, an additional light source is required. Thus, a backlight unit is disposed under the LCD panel, and the LCD device displays images using light produced by the backlight unit.
Among the various types of LCD devices commonly used, active matrix LCD (AM-LCD) devices have been developed because of their high resolution and superiority in displaying moving images. Generally, the AM-LCD device includes a first substrate having a thin film transistor (TFT) in each pixel region as a switching device, a pixel electrode in each pixel region, and a second substrate having a black matrix corresponding to a boundary between the pixel regions. Additionally, the AM-LCD device includes red, blue, and green color filters that correspond to each of the pixel regions, and a common electrode over the black matrix and the color filter layer.
FIG. 1 is a schematic perspective view of an LCD device according to the related art. As shown in the figure, the LCD device 1 includes an LCD panel 2 and a backlight unit under the LCD panel 2 as a light source. The LCD panel 2 includes a first substrate 10, a second substrate 12 facing the first substrate 10, and a liquid crystal layer (not shown) interposed between the first and second substrates 10 and 12. Although not shown, the first substrate 10 includes a first display region and a non-display region, and the second substrate 12 includes a second display region corresponding to the first display region, wherein the second substrate 12 expose the non-display region of the first substrate 10. Also, although not shown, a plurality of gate lines and a plurality of data lines are formed in the first display region, and a plurality of gate pads and a plurality of data pads in the non-display region are connected to the plurality of gate lines and the plurality of data lines, respectively.
The plurality of gate pads and the plurality of data pads are connected to a printed circuit board (PCB) 40 through a flexible printed circuit (FPC) 20 having a plurality of driving integrated circuits (IC) 22. Although not shown, a timing controller, a power supply unit, and a gamma voltage generator are packaged in the PCB 40. Each of the plurality of driving ICs 22 includes a gate driving IC (not shown) generating and outputting a scanning signal for transmitting to the plurality of the gate lines, and a data driving IC (not shown) generating and outputting an image signal for transmitting to the plurality of data lines through a signal voltage from the PCB 40.
When the LCD device 1 displays an image using the driving IC 22, a high temperature condition gradually occurs in the respective driving ICs 22. Accordingly, the life of the driving IC 22 is reduced and results in signal distortion that reduces image quality due to the effects of elevated temperatures, which reduces image quality. The size of the LCD device 1 is proportional to the number of driving ICs 22. Therefore, the more driving ICs required, the more that structures need to be provided to control temperature of the LCD device 1, specifically the more heat that needs to be removed during operation.
FIG. 2 is a simulation view showing a driving IC 22 for a LCD device according to the related art. The formality temperature of the driving IC 22 is, about 85 Celsius degrees. FIG. 2 shows a maximum exothermic temperature of the driving IC 22 of 102.7 degrees Celsius, which is much higher than the formality temperature.
Further, because the FPC with the driving IC has a very low thermal conductivity, the large amount of heat in the FPC is not readily transferred away from the driving IC.